A semiconductor device includes a substrate having first to fourth regions, a first insulating film formed on the substrate in the first region, a first epitaxial layer formed on the substrate in the second region and having an upper surface higher than an upper surface of the first insulating film, a first semiconductor layer formed on the first insulating film with a space provided with respect to the first epitaxial layer and having an upper surface set at substantially the same height as the upper surface of the first epitaxial layer, and an element isolation insulating film formed in the space and having an upper surface set at substantially the same height as the upper surface of the first epitaxial layer and the upper surface of the first semiconductor layer.